In the manufacturing process of a semiconductor device, a resist such as a photoresist is used since an impurity region is formed in a semiconductor substrate. The method for forming an impurity region includes, for example, a method in which an element capable of forming the impurity region is ionized from a compound containing the element and ions thus obtained are allowed to collide with a semiconductor substrate (hereinafter referred to as “ion implantation”) or a method in which a compound containing an element capable of forming the impurity region is exposed to a semiconductor substrate (hereinafter referred to as “dopant exposure”). For example, a resist film formed on a semiconductor substrate is irradiated with active chemical rays through a mask or reticle having a desired pattern, developed with a developing solution, and then cured by heating (hereinafter referred to as “thermal curing”) to form a cured pattern of the resist film. The cured pattern thus formed is allowed to undergo ion implantation or dopant exposure through an ion implantation mask or a dopant exposure mask to form an impurity region having a desired pattern shape.
When the impurity region is formed in the semiconductor substrate by ion implantation or dopant exposure, the impurity region is formed in a desired pattern shape, so that the ion implantation mask and the dopant exposure mask are required to have patternability with high resolution. Low ion implantation temperature during ion implantation may lead damage to a crystal structure of the substrate due to ions collided with the substrate, thus failing to forma low resistance layer. Likewise, low dopant exposure temperature during dopant exposure may lead insufficient diffusion of ions into the substrate, thus failing to form a low resistance layer. Therefore, the ion implantation mask and the dopant exposure mask are required to have high heat resistance and cracking resistance. Particularly, during ion implantation, ions accelerated by high energy collide, so that surplus heat is generated by collision energy. Therefore, the ion implantation mask is required to have enough heat resistance and cracking resistance to withstand impact during ion implantation.
In general, a photoresist has excellent patternability with high resolution, but has poor heat resistance. A silicon dioxide (SiO2) film formed by a chemical vapor deposition (CVD) method is required to be patterned by dry etching using a photoresist so as to form a fine pattern. Therefore, there arises a problem that the step becomes complicated. Accordingly, there has been required a photosensitive resin composition which is capable of forming a pattern with high resolution, and also has high heat resistance and high cracking resistance.
When an impurity region is formed in a semiconductor substrate, a resist film sometimes deteriorates by a reaction between a liquid or gas and a resist film to be used in dopant exposure, or ion implantation or dopant exposure to the resist film. Furthermore, an organic substance in a resist film sometimes deteriorates to form a slightly soluble compound, depending on the composition of the resist film. Such deterioration of the resist film in formation of the impurity region leads to deterioration of solubility of the resist film in a resist peeling liquid, thus causing formation of residues after removal of the resist film. Therefore, there has been required a method in which a resist film and a cured film deteriorated in formation of the impurity region are removed without forming residues.
There has been known, as a photosensitive resin composition having high heat resistance, a photosensitive resin composition containing a polysiloxane, and the photosensitive resin composition has been used as a cured film such as an insulating film. The photosensitive resin composition includes, for example, a positive or negative photosensitive resin composition containing a polysiloxane, a naphthoquinone azide compound, or a photoacid generator or a photocrosslinking agent (see, for example, Patent Literature 1), and a positive photosensitive resin composition containing a polysiloxane and a naphthoquinone azide compound (see, for example, Patent Literature 2).